Treatment of tall oil acids



C. R.'BROWN ETAL TREATMENT 0F TALL oIL ACIDS Sept. 1, 1942.

2 Sheets-Sheet .1

Filed June l2, 1940 ATTORNEY l, 1942. n lc.. R. BROWN ETYAL 2,294,443 2 TREATMENT 0Fv TALL OILL ACiDs Step.,

2 sheets-sheet 2 Y Filed Junev l2, 1940 do, d

ATTORNEY Patented Sept. 1, 1942 UNITED- STATES PATENT .FFlE

.,...Mafzllmms *I Scott, Ardmore, Pa., assignors to The Sharples.- Corporation, Philadelphia, Pa., a corporation of Delaware l Application June 12, 1940, seria1Nc.s4o,o26

' y j iofcmms. (cl. 26o-97.5)

The present invention pertains to treatment of mixtures of fatty acids and resin acids obtained from natural sources, in order to separate these acids from each other and from other constituhigh yields of the desired products yare obtained. A further object'has been to avoid the defects inherent in the s'olvent extraction process, in

' that products of improved purity are obtained,

` the present invention consist peierably only of and that the extractants used in the practice of 55 water and materials formed in thefpractice of the process itself.

Further objects, and the manner in which ents with which they may be .admixech It per- A5 they have been attained, will be evident from a tains more particularly to mixturesof these acids reading of the following specification in the light obtained from thetreatment of black liquor in of the attached ow sheet, in which, the sulphate paper manufacturing process. The Figure 1 represents the preferred methodof y mixture known as"tall oilfrepresentsa familiar A practicing the process of the inventiomzand exampleof such a composition. In 'the practice -10 Figure l2 represents an alternative embodiof the present invention, the tall oilwhich isy ment of the invention. j p treated to effect separation of acid constituents Referring to the drawings1 b'y'reference charand recovery of the respective acid values may be acters, the tall loil from container I0 may be' obtained by the processes described in our co-l mixed with a small quantity of a mineral acid pending applications Serial No. 239,114 vand/or such as sulphuric acid (e. g1..- 2 of '70%` acid) 306,460, or it may be tall oilfrom any other suitfrom container II, and the resulting mixture of able source. Mixtures of the fatty and'resin tall oil and acid ysludge maybe passed from the acids with each other which are analogous to the mixer I2 to centrifugal I3. This centrifugal ef-y tall oil of commerce will be hereinafterreferred p fects separation of acid. sludge as the heavier to in the specification and claims as tall oil and phase, and of tall oil as the lighter phase, both it will be understood that this term is used to of these materials being preferably continuously? designate such mixtures regardless of origin, and and separately discharged from the centrifugal. regardless of whether they may be designated 'I'he acid treating step is preferably conducted as tall oil in the strict parlance of commerce. at a temperature which is griot in excess', of 100 Many proposals have been made in the past F. High temperatures "should ,be avoided for solving the problem of separating tally oil throughoutthe practiceV of the process `of the acids from each other and from other ltall oil present invention, and of theprelminarystepsconstituents, such as phytosterol.y Among then by-which the tall oil which enters into the prac` methods proposed for solution 'Qi' this problem,l tice o/f` the invention is obtained, since temperathe most effective have involved' vacuum distillap 30 tures in excess of 220 l. tend to cause decomtion, or selective esteriflcation followed by solvent position of the product.- n y extraction. The method of vacuum distillation The steps of acid treating ,by thorough agita-f is objectionable because of the fact that the tion in the mixer I2 and centrifugal separation yields from such a process are relatively poor,l of the sludge from the tall oilinthe centrifugal since the high temperatures required for the dis- I3 effect removal of oxidized resin acidsancl tillation step even at low pressures cause much other impurities from the product'. .thereby preof the abietic acid tobe decomposed to form venting vthe formation of sludges invconnection` f abietic anhydride. The process of selective eswith the ensuing steps of selective esterication terication, when carefully conducted,avoids this and separation of constituents from eachother. disadvantage, but this process, as practiced' in 40 The step of vacid treating has the additional'ad-v the past in conjunction with solvent extraction, vantage that it eiects formation of certainsulhas also been subject to certain serious disadgfonated products which are retained in the tall vantages, in that the products obtained contain oil and act 'as catalystsin the esterifying step undesirable impurities, and that a good deal of which follows. This simple step of acid treating expense is entailed in connection with the use 'i5'v thus fulfills the dual function of removing conand recovery of the large quantities of solvents stituents which inhibit the eflicient performance required. n 1 of subsequent steps Vof the process, and ofform- An object of the present invention has been ing Compounds Whih act aS catalysts andthus to provide aprocess which would avoid the difnrender .the introduction 0f Special catalysts .un-1 culty inherent inthe distillation process, in that necessary.

The eiiluent :from vthe centrifugal I3 is next subjected to esterication with an organic alcohol, and the alcohol used in this esterification step is preferably oneof the lower aliphatic al-f cohols, such as methanol. In the practice of Y In the preferred practice of the invention, no. catalyst is added to the materialbeing subjected to esteriiication, sincev the sulfonated products formed in the preceding acid treating step constitute all of the catalyst necessary. An additional catalyst, such as a mineral acidorother esteriilcation catalyst,v may be added to the material in the reactor I within the spirit of the invention, however. While the presence of such additional catalyst serves to speed up the reaction somewhat, it also introduces a special problem of catalyst recovery which is avoided by the use of the sulfonated products already in the oil as the catalyst. At the conclusion of the esteriilcation reaction, the reaction mixture is subjected to a water washing step to effect removal of the unreacted esterifyi'ng alcohol. As illustrated in the flow sheet, water from container It is added to the reaction mixture in an amount which may involve use of one part of water for .a

each two parts of alcohol which have entered the esteriiication reaction, The water, containingdissolved alcohol, is separated from theV oil in the separator I1.

In case the esterlfying alcohol is operations involve the relative proportionsof materials discussed above, the solution of methyl alcohol and water will separate from the oil in the separator `II as the upper layer, and the tall oil esteriflcation mixture, containing the methyl-esters of the fatty acids, the resin acids and other oily constituents will constitute the lower layer.r This lower layer is preferably subjected to a second step of water washingfto re- Y move further methyl alcohol. 'Ihis second step of water washing may involve addition to the oily layer of an amount of water equal to the amount added before separation in the separator I1. 'I'he water so added will dissolve the re- 0 mainder of thealcohol in the oily eiliuent from the separator I1, and this solution of methyl alcohol will be removed as the heavier layer from the separator I8, while the lighter, 4oily layer, will then be mixed with clay from containerv I9, subjected to dehydration by' blowing air or an inert gas through the oil, as indicated at 20, and passed through the filter 2I to remove theA clay. These steps of clay filtration and dehydration serve to remove water remaining in the oil as the result of the water washing steps, and to remove other impurities which would tend to inhibit thev efllcient performance of the following crystallization step.

It will be noted that the aqueous alcoholic layer forms the lighter layer in the separator I1 when `the operation of water washing is per- .formed'as described above, but that the aqueous water is added in the proportions discussed above methyl alj cohol and the esterification and water washingfrom container II to the material passing to the separator I1, the water does not constitute a sufficiently large proportion of the material` passed to the separator I1 to render the solution of methyl alcohol and water heavier than tall oil. 'I'hemajor part of the methyl alcohol is removed from the tall oil in the separator Il, however, and when further water 'is added from container I6, prior to passing the tall oil to the separator I8, the water preponderates in the aqueous alcoholic solution in the separator Il to suchk an extent as to render this aqueous alcoholic solution layer heavier than the oil layer.

The wash water, which contains the methyl alcohol removed from separators I1 and Il, is passed to a still II, in which it may be subsequently `distilled to recover methyl alcohol, or

of time between 24 and 48 hours, or until approximately of the abietic acid of the mixture has been crystallized from solution.

The mixture from the crystallizer 22'is next lsubjected to a filtering or screening operation to remove the resin acid crystals. This may be 'aclcomplished by passing the mixture 'to a hydroextractor 23 having a suitable filtering or screening surface through which vthe liquid is discharged, Awhile retaining the solidsor dischargingl them separately by continuous or intermittent operation, as will be well understood by those y skilled in the art. The crystals in the hydroextractor 23 may be washed with methyl alcohol from container 24 in order to remove .esters or other impurities which are not desired in the abietic acid crystals. The methyl alcohol wash .liquor from this vpurification step. may be returned to the'esteriilcation step performed in the lreactor I5, in order to recover values from this methyl alcohol wash water, and re-use the methyl alcohol. The washed crystals from the hydro-extractor 23 will be found to be relatively pure abietic acid.

The oily mixture discharged from the hydroextractor 23, containing the methyl estersof the Y fatt-y acids, the portion of the resin acids which were not crystallized in crystalllzer 22, and other constituents including phytosterol, is next mixed with a sufficient quantity of a base to form water soluble soaps by reaction ofthe basel with `the acid constituentsl of the mixture. This is,ac complished byadding a base capable of forming water soluble soaps, such as an alkali metal or ammonium hydroxide, from container 25 and mixing this-added Abase with the oil. The step of neutralization may be accomplished, vfor example, by adding a suillcient quantity of sodium hydroxide of 20 to 25% concentration.

The mixture resulting from addition of sodium hydroxide from the container A2li will contain soaps, esters, and unsaponiflable constituents su'ch as phytosterol. It is desirable, in the practice of the invention, to make a relatively clean separation of each of these constituents from each of the others. In the practice of the inven- -of this water thins the. soap this is vaccomplished without the addition of'anyexpensive solvent. v Thermixtureis rst 'diluted with an amount fof water. from container 26 Vwhich may be between and 4 times the yvolumeofjmaterial under. treatment. The addition relatively -dilute condition,and this thin s oap is separated as the. heavier :phasefrom a continuous Vtice the invention. The soap formed by addition of the mixture to a' centrifugal lseparator 21. vThe-centrifugal separating operation performed in centrifugal 21 is preferably accomplished at perz'tture;y e. g., betweenw200 and 210.F.

airelatively high temf The 'lighterphase'offthe centrifugation con-4 sists-of anemulsion containing esters, unsaponifiable constituents, andsomesoap. This mix.- ture isfdiluted with asubstantial'quantlty of the mixture resulting from neutralization of the'oil eiliuentfromhydrofextractor 23 by the .base from container 25,.and 'is heated to a tempera- -ture .sufficiently high to break the emulsion,this

heating step being preferably performed by passingfthe lmaterials through a heater 28 to heat the mixture to a temperaturefbetween l200 and v The.broken emulsion frornthe heater 28.His

Vpassed to a second centrifugal 29fof the vsaine 'type as centrifugal 21, and the .emulsion isseparatedl in 'that' machinev into a relatively thick soap,- which is theheavy eflluent, andan esterofsodium hydroxidefrom container f`i`s'fprincipallyj sodium abietate This lsoap, in its fooncentrated form, possesses a certaindegreeof sol#v "vent power for the methylesters of the mixture' and .for certain; ofi'y theunsaponiiiable .constituents." 'It is therefore necessary to dilute thesoap with watery from container 26 in order t'o precipitate part of the'oil values ofthe mixture from solution in the'soap. Butwhen a mixture containing'the quantityof water necessaryto ef' Y fect such vprecipitation is subjected to centrifugation in the centrifugal 21, it is impossible to effect a clean-cut separation 'of vsoap from other com stitueuts of the mixture.l While a thin 508D( I which contains very little o'fthemethyl esters or unsaponiflable constituents may be 4discharged from ythe centrifugal 21,;the lighter phasefrom this centrifugal will necessarily contain some soap and fwater, with the result that a considerable degree of emulslflcationA of the constituents of this eiiluent exists. I f

' .When ythe emulsion emuent from the centrifuf vgall v2'( is'mixed l'with a substantiaiquantityvof the thick soapcont'aining'mass resulting from additionof sodium hydroxidevfromcontain'er 25,

this thick soap-containing mass absorbs the ex-v [cessl `water presentinnthe emulsion phase, and

containing-fraction which is almost completelytu free from soap this ester-containing fraction also containing unsaponifiable constituents of the .crude starting material. The esters from the centrifugal 29 are passedto still 88, where they arevsubjected to vacuum vdistillation and passed n' overhead, leaving unsaponiilablev material as residue. The esters removed-fromfthestill, may be subjected to saponiflcation vwith an. alkali such ascaustic sodaand sprung with an acid, in yorder to recover the fatty acids of the esters as such, if the fatty acids lare thenultimately `desired product .rather than tlfie'estersA of. these" acids.

.the resultingniixturecan be subjected to suc`` cessful centrifugation'as indicated at29, provided l itfis'passed t0,;that centrifugal at a temperature j sufficiently [high to insure Hbreaking'of the emul-j.;

'sion.".l.Th e soapveliluentfrom the centrifugal 2'8"y is relatively concentrated, vand by 'reason' oflfits concentration' it containsa certain amount of the, f methylA esters. in solution. I The lighter eiiluent from the centrifugal '29, on thejother handLis substantially free of soap. -The addition of. the' nheavy :soap to the emulsion dischargedA from,-the centrifugal 21 thus has vthe rathersurpris'ing effect in vnet vresult of assisting'in removing the relatively small quantityof soapwh'ich-'is in that The soap discharged from centrifugal 2911s prei-v erably mixed with the material .being passed to the' centrifugal 21.

along with other materials being processed inthe practice ofthe invention, f

In the practical .performance of. the Vintro-stage results have been obtained by dividingthe soapcontaining material, obtained by adding sodium hydroxide from container 125, into two .approximately equal parts. Y The rst such part is diluted with water and centrifuged, as .discussed in connection with elements 26 and 21 'of theflowsheet.

centrifugal separating step discussed above, Abest y n Y :discharged from the centrifugaifzs with the stap' emulsion 'prior to additionof this heavy soap.

, From `the above discussion,jit will be evident that, itis desirable to adjustv the etmtrifugai= 29 in suonav 'manner as toobtain a light, ester phase, eilluent which is relatively free ofthe Vsoap phase. On the other hand, it isdesirable that the centrlfugal21 be adjusted in sucha'wayas tof-.pri-

duce afsoapwphase which is relatively free'of the J' ester and unsaponifiable constituent phase. The emciencyof, the operatlon'is not greatly impaired by reason of. the' discharge of a certain amount of soap with the. emulsionr phase from the cen-v trifugai ziyor'tecause of the fact that part of the estersand unsaponiiiable'constituents may be phase. presence of a certain amount of esters and unsaponlflable constituents in the soap eillue t from the centrifugal 29 is inevtableln anypcase, since .the soap, in the concentration invlvedg has some 'solvent power yfor these con- The secondpart is mixedywith trannyl emuent 1 from centrifugal 21 as Adiscussed above, and passed' through the heater 28 and'fthe centrifugal ing mixed with vthe thin Asoap-containing mixture passing to the centrifugal 21, as' indicated on the flow sheet.

students. 1t. is to be' noted. howeyer, that ysoap ,is'f'passed linto'contafct with a very' much 29, the soap eiiiuent froxn'fthe centrifugal 29 belmore dilute soap, and is subjected to efflcient'centrifugation inthe ,centrifugal 2iv to recover estersy vand unsaponiflable constituents therefrom. .Sinn

Iilarly, the emulsion phase discharged from the the theory underlying the steps performed by the elements 25 to 2S of the flow sheet will be helpful in enabling those skilled in the art to prac- .centrifugal 21 is subjected to mixingv with conf-- -centrated soap, heating, and a further step of centrifugation, in .order-that the soap and'. water may be removedwlth reasonable thoroughness from this emulsion phase. The functions of the 1 centrifugals 21 and za are thus,v in aange, 0pmsite, it kbeing the ltlmztloll of the centrifugal 21 to remove practically all of the esters and unsaponifiable constituents from the soap, and the function ofthe centrifugal 29 to remove practically all of the soapand water from the esters. In connection with each centrifugal', the job of cleaning up the impure effluent is passed `on to the other centrifugal.l

A great many modifications are possible within the spirit of the invention. Thus, instead of using relatively purewater from the container 25` to dilute the viscous soap-containing mass be fore-passing this material to the centrifugal 21, part or all of the alcohol-containing wash water from thestill 3l, resulting from washing the original esterification mixture, may be used to effect this dilution. We prefer, however, to use relatively pure water in this step of dilution, since this simplifies the subsequent purification steps. As a further alternative, the emulsion eilluent from the centrifugal 21 may be separated into its constituents by a solvent extraction step to effect separation of Water and soap from the organic constituents, instead of treatingthis emulsion with a further quantity of soap, as described in connection with the elements 28 and 29 of the flow sheet.

The steps of clay treating, dehydrating, crystallizing abietic acid and removing the crystallized product from the esterified mixture may be entirely omitted within the spirit'of the invention, although these features are very useful, It would be possible to subject the o ily mixture passing from the separator IB directly to treatment with a base, and practice the features ofthe invention following such treatment' and described in connection with flowy sheet numerals 25 to 30, within cohol. such as methyl, ethyl or propyl alcohol from container Il, and these constituents are heated in esteriiication kettle 4.2 until substantially all of the fatty acids of the tall oil have been esteriiled. This esteriflcation reaction may be catalyzed by sulfonic compounds remaining in the tali oil as the result of an acid treating step such 'as that described in connection with Figure any part of the abietic' acid prior to the steps of y treatment with a base, treatment With/water and vsuccessive steps of centrifugation as described.

It is possible to employ many other features than those described in the practice of the inf vention, 'or to adopt still further modifications `performance ofa succession of water washing steps to remove esters and unsaponifiable' constituents from the soap-containing ,mixture it would be possible to effect a fair degree of separation of esters and unsaponifiable constituents in a single step of centrifugation. Incase this operation is performed in a single step, it will usually be desirable to eli-minate the addition of water to the soap-containing mass before passing this mass to the centrifugal 21, or at least to dccrease the proportion of such water below the proportion indicated in connection with the preferred embodiment of the invention. V l

Figure 2 of the drawings represents a modification of the invention which is not considered to be as desirable as Figure 1, but which affords good results. In this embodiment, tall oil from container 40 is mixed with a lower aliphatic al- 1, or a small amount of dry hydrochloric acid. or of sulfuric acid, may be used as the catalyst.

At the conclusion of the esterification reaction, the esteriflcation mixture is washed with water from container 43, and the mixture of water, alcohol and catalyst resulting from vthis washing operation is passed to mixer 4I. The mixture of ester and resin acids is passed-to a crystallizer 45 (preferably after drying as in connection with Figure 1), and the crystallized abietic acid is removed from other constituents of the mixture in hydro-extractor 46, the crystallizing and hydroextracting steps being similar to those performed in connection with Figure 1 of the flow sheet. The liquid from hydro-extractor 46 is mixed with saponifying reagent from container 41 to effect saponificationof Athe remaining abietic .acid as in connection with Figure 1 of the drawings. and the resulting soap-containing mass is then passed to mixer 44 and mixed with the aqueous effluent which has been passed to that mixer from the esteriflcation kettle. i After the soap is thoroughly mixed with the aqueous material in the mixer 44, the mixture is allowed to stand, and 70% of the esters of the soap-containing mass separate from, the remaining material in the mixer as the lighter phase. These esters are drawn off from the mixture of soap, water, unsaponifiable constituents, etc. After removal of the majority of the esters as discussed above, the remaining material in` the mixer u is mixed with'an organic solvent to effect removal of the remaining esters and unsaponifiable constituents from the remaining soap and'water. This treatment may be accomplished Aby adding a sufiicient amount of naphtha from container Il to dissolve the esters and unsaponiflable constituents, and the gextracted constituents, together with the naphtha solvent, are then passed to a still I9,- where the naphtha, esters and unsapon'ifiable constituents are separated from each other by distillation.

It will be noted that in this embodiment of the invention, as in the` embodiment of Figure `1, we take advantage of the 'fact that the esters can be separated-to a large extent from the soap with which they are contaminated, by subjecting the soap to treatment withan aqueous liquid. The embodiment of Figure 2 yof the drawings differs fundamentally from that of Figure 1, however, in. that the further separationof esters and unsaponifiable constituents vis accomplished by an extracting step involving dual solvent action, in which the methyl alcohol dissolves the soap and water, and the naphtha dissolves thev esters and unsaponiflable constituents.

Still further modifications will `be obvious to those skilled in the art, and we do not therefore wish to be `limited except by the scope of the following claims.

We claim:V

1. In the treatment of a mixture of resin acids and fatty acid esters resultingfrom selective esterification of 'tall oil with a lower aliphaticA alcohol, the steps comprising neutralizing said mixture by mixing therewith a base which forms water soluble soap with the acids of said mixture, thereafter adding water to the resulting soapmixture with said separated ester-phase and subjecting this final mixture to a second step of-centrifugation to separate soap therefrom.

2. A process asy defined in claim l, in which the soap obtained from said last-mentioned step of centrifugation is mixed with further material passing to said first-mentioned step of centrifugation.

3. In the treatment of al mixture obtained by subjecting tall oil to selective esterification with a lower aliphatic alcohol to effect esterification of fatty acids to the substantial exclusion of resin acids, the process comprising selectively crystallizing a portion of the resin acid content of the mixture and removing the crystallized resin acids from the mixture, mixing the resulting mixture from which a part of thc resin acids have been removed by selective crystallization with abase capable offorming water soluble soaps with the resin acid content of the mixture to form a mixture of the fatty acid esters with soap formed by neutralization of resin acids by said base, adjusting the water'content of said mixture to produce an aqueous soap phase and an ester phase immiscible with said aqueous soap phase, and

` separating said phases from each other.

4. In the treatment of a mixture obtained by subjecting tall oil to selective esterification withv a lower aliphatic alcohol to effect esterification of fatty acids to the substantial exclusion vof resin acids, the process comprisingselectively crystallizing a portion of the resin acid content ofv the mixture and removing the crystallized resin acids from the mixture, mixing the resulting mixture from which a part of the resin acids have been removed by selective crystallization with a base capable kof forming water soluble soaps with the resin acid content of the mixture to forma mixture of `the fatty acid esters with soap formed by neutralization of resin acids by said base, adjusting the water content of said mixture to produce 'an aqueous soap phase andv 'an ester phase immiscible with said aqueous soap phase, and separating said phases from each other by centrifugation. l

5. In the treatment of a mixture obtained by subjecting tall oil to selective esterication with a lower aliphatic alcohol to effect esterif-ication -of fatty acids to the substantial exclusion of resin acids, the process comprising selectively crystallizing a portion of the resin acid content of the mixture and removing the crystallized'resinacids from the mixture, mixing the resulting mixture from which a part of the resin acids have' been removed by selective crystallization with a base capable of forming water soluble soaps with the resin acid content of the mixture to form a mixture of the fatty acid esters with soap formed by neutralization of resin acids by said base, andA thereafter separating said soap from said resin acids. l

6. A process as defined in claim 5, in which the separationof soap is accomplishedby adding water and a hydrocarbon solvent to the mixture resulting from addition of a base to the mixture of tall oil acids, and separating the resulting aqueous soap and ester phases fromy each other by subsidence.

"7. In the treatment of a mixture obtained by subjecting tall oil to selective esterification with of fatty acids to rthe substantial exclusion of resin acids, the process comprising selectively crystallizing a portion of the resin acid content of the mixture and removing the crystallized resin acids from the mixture, mixing the resulting mixture from which a part of the resin acids have been removed by selective crystallization with a base capable of forming water soluble A soaps with the resin acid content of the mixture to form a mixture'of the fatty vacid esters with soap formed by neutralization of resin acids by said base, adding water to a portion of the mixture of fatty acid esters with soap so obtained tor produce an aqueous soap phase and an ester phase immiscible with said aqueous soap phase, `sep arating said phases from each other, thereafter adding a second lportion of the mixtureof fatty acid esters with soap formed by neutralization of resin acids by said base to the ester phase separated from said aqueous soap phase, and separating the soap phase of the mixture produced by this last-mentioned step from the ester phase so produced.

8. In kthe treatment of a mixture obtained by subjecting tall oil to selective esterification with a lower aliphatic alcohol to effect esteriflcation of fatty acids to the substantial exclusion of resin acids, ythe process comprising selectively crystallizing a portion of the resin acid content of the mixture and removing the crystallized resin acids from the mixture, mixing the resulting' mixturev from which a part of the resin acids have been removed by Aselective crystallization with a base capable of forming Iwater solublev soaps with the resin acid content of the mixture to form a mixture of the fatty acid esters with soap formed lby neutralization of resin acids by `said base, adding water to a portion of the mixture of -fatty acid esters with soap so obtained to produce an aqueous soap phase and an ester phase immiscible with said aqueous soap phase, vseparating said phases from each other y by centrifugation, thereafter adding a second portion of the mixture of fatty acid esters with soap formed by neutralization of resin acids by said base to the ester phase separated from said aqueous soap phase, and gationthe soap phase of the mixture produced by this last-mentioned step from the ester phase so produced.

9. In-the treatment of a mixture of resin acids and fatty acid esters resulting from selective esterication of tall oil with a lower aliphatic alcohol, the steps comprising neutralizing said mixture by mixing therewith a base which forms water soluble soap with the acids of said mixture, thereafter adding water to the resulting soapcontaining mixture t0 produce anr aqueous soap phase and an ester phase immiscible with said aqueous soap phase, subjecting said mixture to subsidence separation to separate said phases from each other, mixing a further quantity of the original'soap-containing mixture with said separated ester phase and subjecting this final mixy of subsidence separation is mixed with further v material passing to said first-mentioned step of subsidence separation.

ASHTON 'I'. sco'r'r. CHARLES R. BRQWN.

a lower aliphatic alcohol to effect esterication A separating by centrifu- 

